Stump grinder having an automatic depth control system

ABSTRACT

An automatic depth controlled cutting assembly for a stump grinder includes a cutting assembly operatively attached to a stump grinder for engaging and grinding a stump, an actuating assembly to actuate movement of the cutting assembly relative to the stump, and an automatic depth control system cooperating with the actuating assembly to automatically control a depth of the cutting assembly relative to the stump.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.11/796,074, entitled “STUMP GRINDER HAVING AN AUTOMATIC DEPTH CONTROLSYSTEM” which was filed on Apr. 26, 2007 and is currently pending, thecontents of which are incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to stump grinders and, moreparticularly, to a stump grinder having an automatic depth controlsystem.

2. Description of the Related Art

It is known to provide a stomp grinder for grinding undesirable treeslumps. Typically, a stump grinder includes a frame, an engine or otherdrive mechanism such as a belt tension engagement mounted to the frame,a cutting assembly having a boom pivotally secured to the frame, and arotatable cutting wheel operatively supported by the boom and driven bythe engine. The stump grinder also includes an actuating assembly tomove the stump grinder and/or cutting assembly relative to the stump.Such actuating assemblies are typically hydraulic in nature, but mayalso be pneumatic, electronic, or mechanical. The stump grinder furtherincludes a control system to control the direction and rate of movementof the actuating assembly. Such control systems are typically electronicin nature, but may be hydraulic, pneumatic, or mechanical.

During removal of a tree stump from a landscape, an operator directs themovement of the actuating assembly through the control system to causethe cutting assembly to engage a portion of the stump. As the cuttingassembly engages the stump, the operator will typically laterallyadvance or feed the rotatable cutting wheel across an upper surface ofthe stump, grinding away a top portion of the stump. Upon completion ofa lateral pass across the stump, the operator will direct the cuttingassembly in a downward manner through the control system to engage thetop surface of the stump and once again direct the rotatable cuttingwheel across the upper surface of the stump in a lateral motion. Thisprocess is repeated until the stump is completely ground to anacceptable depth, which is typically below a grade of the landscape.Thus, the manner in which the operator controls the actuating assemblythrough the control system will directly affect the rate at which thecutting assembly will grind a stump.

Accordingly, the productivity of the stump grinder is dependent on theoperator to maintain an appropriate rate of speed and depth of thecutting assembly into the stump. Placing the cutting assembly at toogreat a depth into the stump will slow the rotation of the cuttingassembly and overwork the engine, which may result in engine stall orpart failure. When the engine stalls or a part fails, the stump grindermay become plugged or otherwise inoperable. As a result, the stumpgrinder has to be unplugged or serviced, the engine restarted, and thenredirected at the stump. This is a relatively time consuming and laborintensive process, resulting in higher costs, which is undesired.Conversely, placing the cutting assembly at too little depth into thestump will under-work the engine causing a more time consuming processthan otherwise necessary, resulting in a loss of productivity and higheroperational costs.

Conventionally, maintaining a balance between overworking andunder-working the engine is based on an operator's sensory perception ofa working stump grinder. By way of example, an operator makes a depthadjustment based on engine sound or vibration felt in the controls.However, an operator's sensory perception is highly subjective relativeto one's skill/experience, ambient conditions, stump condition, etc. andtherefore subject to a loss of maximum efficiency.

While known stump grinders have generally worked for their intendedpurpose, there remains a need in the art for stump grinders that provideimproved output efficiency. More specifically, there is a need in theart to provide a stump grinder that overcomes the disadvantage ofoverworking or under-working the engine as a result of improper depthplacement of the cutting assembly into a stump during operation.Therefore, there is a need in the art for a stump grinder that overcomesthe above disadvantages by having a control system that automaticallysets the depth of the cutting assembly during operation.

SUMMARY OF THE INVENTION

Accordingly, the present invention is an automatic depth controlledcutting assembly for a stump grinder includes a cutting assemblyoperatively attached to a stump grinder for engaging and grinding astump. The automatic depth controlled cutting assembly also includes anactuating assembly to actuate movement of the cutting assembly relativeto the stump. The automatic depth controlled cutting assembly furtherincludes an automatic depth control system cooperating with theactuating assembly to automatically control a depth of the cuttingassembly relative to the stump.

In addition, the present invention is a stump grinder including a frameand a cutting assembly operatively supported by the frame. The stumpgrinder also includes an actuating assembly operatively connected to theframe to actuate operational movement of the cutting assembly relativeto the stump. The stump grinder further includes an automatic depthcontrol system cooperating with the actuating assembly to automaticallycontrol a depth of the cutting assembly relative to the stump.

One advantage of the present invention is that an automatic depthcontrol system is provided for a stump grinder. Another advantage of thepresent invention is that the automatic depth control system directsoperational movement of a cutting assembly of the stump grinder relativeto a stump from a first position to a second position that is apredetermined distance away from the first position for improved stumpgrinding efficiency. Yet another advantage of the present invention isthat the automatic depth control system enables the operator to directthe cutting assembly to a selected, predetermined depth after eachlateral movement across the stump for improved output efficiency. Afurther advantage of the present invention is that the automatic depthcontrol system is integrated within a control system that can be usedwith an actuating assembly of the stump grinder that is poweredhydraulically, electronically, or pneumatically.

Other features and advantages of the present invention will be readilyappreciated, as the same becomes better understood, after reading thesubsequent description when taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of an automatic depth control system,according to the present invention, illustrated in operationalrelationship with a stump grinder.

FIG. 2A is a side elevational view of the automatic depth control systemand stump grinder of FIG. 1 in a first position.

FIG. 2B is a view similar to FIG. 2A illustrating a downward verticalmovement of a cutting assembly of the stump grinder from the firstposition illustrated in FIG. 2A to a second position in response to theautomatic depth control system.

FIG. 3 is a schematic diagram of a control system having the automaticdepth control system illustrated in FIG. 1, according to one embodimentof the present invention.

FIG. 4 is a schematic diagram of a control system having the automaticdepth control system illustrated in FIG. 1, according to anotherembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings and in particular FIGS. 1 through 2A, oneembodiment of a stump grinder 10, according to the present invention, isshown. The stump grinder 10 includes a frame, generally indicated at 12.The frame 12 extends longitudinally. The stump grinder 10 also includesa hitch assembly 14 at one longitudinal end of the frame 12 to receive ahitch of a vehicle (not shown) for towing behind the vehicle. The stumpgrinder 10 includes an axle 16 rotatably supported by the frame 12,wheel rims 18 operatively connected to the axle 16, and tires 20attached to the wheel rims 18 to facilitate movement of the stumpgrinder 10 during transportation and movement relative to a stump (S).

As illustrated in FIGS. 1 through 2A, the frame 12 includes a first orlower section 22 and a second or upper section 24 operatively supportedby the lower section 22. The upper section 24 is disposed over the lowersection 22 and movable relative to the lower section 22. The lowersection 22 includes an operational viewing window 26 and an arm 28pivotally mounted relative to the frame 12 about a pivot point 30. Theoperational viewing window 26 is connected to the arm 28. Theoperational viewing window 26 provides an operator (not shown) of thestump grinder 10 with shielded viewing access during operation. Itshould be appreciated that the arm 28 may be jointed to further positionthe operational viewing window 26 or may include a telescoping featureto further extend the operational viewing window 26 relative to theframe 12.

The lower section 22 also includes a flexible curtain 32 that depends orhangs from the frame 12 to shield the legs of an operator (not shown)from comminuted stump material that may be thrown during operation. Thecurtain 32 may extend around the rear and sides of the frame 12 or mayexclusively extend below the operational viewing window 26.

The frame 12 includes a connector member 34 pivotally attaching theupper section 24 to the lower section 22. The connector member 34 has afirst pivot pin 36 disposed along a horizontal axis and connected to thelower section 22. The first pivot pin 36 permits the upper section 24 tomove in a vertical manner relative to the lower section 22 (FIGS. 2A and2B). The connector member 34 further includes a second pivot pin 38disposed along a vertical axis and connected to the upper section 21.The second pivot pin 38 permits the upper section 24 to move in alateral manner relative to the lower section 22. It should beappreciated that pivoting of the frame 12 enables movement of the stumpgrinder 10 relative to the stump (S) for efficient operation. It shouldalso be appreciated that, without pivoting movement, the presentinvention would require a towing vehicle (not shown) to re-position thestump grinder 10 to effectively remove the stump (S) from a landscape.

Both the upper and lower sections 22, 24 are generally constructed ofmetal such as steel and are generally rectangular in cross-section. Itshould be appreciated that the upper and lower sections 22, 24 of theframe 12 may be constructed from any material suitable for use inconnection with stump grinding and may have any suitable cross-sectionalshape. It should also be appreciated that, while the frame 12 is shownin a bisected manner, the frame 12 may be of a unitary construction andpivoting maintained through pivotal movement of a cutting assembly,generally indicated at 40 and to be described, relative to the frame 12.

The stump grinder 10 further includes a drive assembly, generallyindicated at 42, to drive the cutting assembly 40. The drive assembly 42is mounted to the frame 12. The drive assembly 42 includes an engine 44operatively coupled to the cutting assembly 40 by a drive mechanism (notshown). It should be appreciated that the drive mechanism may include adrive shaft, belt, or chain drive adapted to drive the cutting assembly40.

Referring to FIGS. 1 through 2B, the drive assembly 42 further includesat least one, preferably a plurality of pulleys 50, 52, 54 and belts 46,48 disposed over and interconnecting the pulleys 50, 52, 54. The drivemechanism 42 may include other pulleys (not shown). It should beappreciated that the engine 44 may be an internal combustion engine ormay operate through some other manner. It should also be appreciatedthat while the engine 44 is shown operatively mounted to the uppersection 24 of the frame 12, the engine 44 may be remotely locatedrelative to the stump grinder 10 and operatively connected to thecutting assembly 40 by the drive assembly 42 such as in a power take-off(PTO) system (not shown).

The stump grinder 10 further includes a cutting assembly 40 operativelycoupled to the drive assembly 42. The cutting assembly 40 includes aboom 58 operatively supported by the frame 12 at one end and a cuttingwheel 60 rotatably connected at the other end of the boom 58. Thecutting wheel 60 rotates relative to the boom 58 and includes aplurality of cutting teeth, generally indicated at 62, to engage thestump (S). It should be appreciated that the cutting wheel 60 isoperatively coupled to the engine 44 by the drive mechanism (not shown).

As illustrated in FIGS. 1 through 2B, the cutting teeth 62 include aprimary set 64 having a primary function of engaging the stump (S) and asecondary set 66 adjacent the primary set 64 for removing the comminutedmaterial away from the primary set 64. The cutting assembly 40 furtherincludes a guard 68 disposed adjacent and connected to the boom 58 tocover a top section of the cutting wheel 60. The guard 68 preventscomminuted material from being ejected in an upward manner. It should beappreciated that the cutting wheel 60 may include a plurality of ahooks, knives, or bars (not shown) to convert the stump (S) intocomminuted material.

Referring now to FIGS. 1 through 3, the stump grinder 10 includes anactuating assembly, according to the present invention and generallyindicated at 70, to actuate movement of the cutting assembly 40 relativeto the stump (S). The actuating assembly 70 is operatively connected tothe connector member 34 and to the cutting assembly 40. In theillustrated embodiment, the actuating assembly 70 is powered byhydraulic fluid and is in operative communication with the driveassembly 42 to provide power for delivery of pressurized hydraulic fluidsuch as oil. It should be appreciated that the actuating assembly 70 mayalso be powered pneumatically or electrically.

The actuating assembly 70 includes a pump 71 and a plurality of fluidcylinders 72, 74, 76, 78 fluidly connected to the pump 71. The pump 71is operatively connected to the drive assembly 42 and/or engine 44 topump pressurized fluid to the fluid cylinders 72, 74, 76, 78. It shouldbe appreciated that each of the fluid cylinders 72, 74, 76, 78 includesan inlet port and an outlet port through which pressurized fluid isdirected in/out of the fluid cylinders 72, 74, 76, 78 during operation.

The fluid cylinders 72, 74, 76, 78 actuate movement of the cuttingassembly 40 relative to the stump (S). Specifically, the fluid cylinder72 is a tongue cylinder to actuate the stump grinder 10 in a fore andaft movement relative to the stump (S) (FIGS. 1 through 2A). The fluidcylinder 74 is a vertical cylinder to actuate the upper section 24 ofthe frame 12 in a vertical manner about the first pivot pin 36 (FIGS. 2Athrough 2B) to adjust the depth of the cutting assembly 40 relative to astump (S). It should further be appreciated the fluid cylinder 74 may beoperatively engaged to the stump grinder 10 so as to actuate only thecutting assembly 40 in a vertical manner to facilitate depth adjustmentrelative to a stump (S).

The fluid cylinders 76 and 78 are a pair of swing cylinders to actuatethe upper section 24 of the frame 12 in a lateral movement about thesecond pivot pin 38. As illustrated in FIGS. 1 through 2B, the two fluidcylinders 76 and 78 act as swing cylinders for actuating the cuttingwheel 60 in a lateral motion across the stump (S) while only one fluidcylinder 72 or 74 is employed for actuating the cutting wheel 60 ineither a vertical or fore/aft motion. It should be appreciated that thestump grinder 10 may include any number of fluid cylinders to actuate adesired motion of the cutting assembly 40.

The actuating assembly 70 further includes a storage tank 80 and a feedmanifold 82. The storage tank 80 and the feed manifold 82 areoperatively connected to the pump 71 through fluid lines wherein thepump 71 is disposed or connected between the storage tank 80 and thefeed manifold 82. The feed manifold 82 receives pressurized fluid fromthe pump 71 and directs it to the appropriate fluid cylinder(s) 72, 74,76 and 78 to actuate the desired movement of the stump grinder 10. Itshould be appreciated that pump 71, storage tank 80, and feed manifold82, as well as the other components of the actuating assembly 70 areinterconnected by a plurality of fluid lines. It should further beappreciated that a pressure relief mechanism (not shown) can be disposedalong any fluid supply line as needed.

The actuating assembly 70 further includes an actuator block 84. Theactuator block 84 receives pressurized fluid from the feed manifold 82and regulates the flow of pressurized fluid toward and away from thecylinders 72, 74, 76 and 78 in response to controls from an automaticdepth control system 86 to be described.

Referring to FIG. 3, the stump grinder 10 further includes an automaticdepth control system, generally indicated at 86, to automaticallycontrol the depth of the cutting assembly 40. In one embodiment, theautomatic depth control system 86 includes a receiver 88 operativelyconnected to the actuating assembly 70. More specifically, the receiver88 is operatively connected to the actuator block 84 to controldirection of fluid through the actuator block 84 to the cylinders 72,74, 76 and 78 in response to operator input, thereby controlling theoperational movement of the stump grinder 10 or the cutting assembly 40.It should be appreciated that the receiver 88 is an electrical devicereceiving power from a power source (not shown) and receives signalsfrom a controller 90 to be described.

The automatic depth control system 86 further includes a controller,generally indicated at 90, to transmit a signal to the receiver 88 orotherwise electronically communicate with the receiver 88. Asillustrated in FIG. 3, the controller 90 is a remote control unitadapted to communicate with the receiver 88 through radio frequencysignals. It should be appreciated that controller 90 may be fixed to thestump grinder 10 or may be removed from the frame 12, while remaininghardwired to the receiver 88 (i.e. tethered) to provide the operatorwith a more suitable viewing angle of the operational movement of thecutting assembly 40.

The controller 90 includes a plurality of controls including anemergency off button 92 to stop the operation of the stump grinder 10.The controller 90 further includes at least one actuating member,generally indicated at 94, to signal the receiver 88 to actuate thecutting assembly 40. As illustrated in FIG. 3 the controller 90 includesthree actuating members 94 in the form of toggle switches 94(A), 94(B),and 94(C). The toggle switches 94(A), 94(B) and 94(C) enable theoperator to move the stump grinder 10 in the vertical direction, lateraldirection, and in the axial direction, respectively. It should beappreciated that the actuating members 94 may be constructed from othercontrol devices, such as buttons, knobs, a joystick, or multiplejoysticks.

During operation of the stump grinder 10, the drive assembly 42 rotatescutting assembly 40. Additionally, the pump 71 directs pressurized fluidfrom the storage tank 80 to the feed manifold 82, which transfers fluidto the actuator block 84. When the operator moves the actuating member94 on the controller 90, a signal is transmitted to the receiver 88. Thereceiver 88 processes the signal and supplies voltage to a coil (notshown) that directs the actuator block 84 to allow pressurized fluid toflow toward or away from one or more of the cylinders 72, 74, 76 and 78for a predetermined time. The predetermined time that voltage issupplied to the coil is controlled by how long the operator continues tohold the actuating member 94 in a particular position. It should beappreciated that, as a result, the movement of the stump grinder 10 iscontrolled entirely by the operator.

The automatic depth control system 86, according to the presentinvention, includes an automatic depth control circuit 96. The automaticdepth control circuit 96 enables the operator to engage or “bump” thetoggle switch 94A to affect consistent vertical movement of the cuttingassembly 40 from a first position (X) (FIG. 2A) to a second position (Y)(FIG. 2B) that is a predetermined distance from the first position (X)(hereinafter referred to as a “predetermined length of travel”). Itshould be appreciated that the predetermined length of travel mayinclude a single movement from a range between less than one half inchto six inches, with a preferred range between one half inch and threeand one half inches.

Referring to one embodiment of the automatic depth control system 86illustrated in FIG. 3, the automatic depth control circuit 96 is locatedwithin the receiver 88 and regulates the manner in which the automaticdepth control system 86 directs the actuator block 81 to move fluid tothe cylinder 74. More specifically, upon receipt of the “bump” signalfrom the controller 90 corresponding to the toggle switch 94A, theautomatic depth control circuit 96 within the receiver 88 will supplyvoltage to a coil (not shown) of the actuator block 84 to direct theactuator block 84 to open a valve (not shown) therein corresponding tothe cylinder 74 for a predetermined time. Where the predetermined lengthof travel is one half inch, the voltage is supplied at a rate of 130milliseconds (ms) and where the predetermined depth adjustment is threeinches, the voltage is supplied at a rate of 780 ms. It should beappreciated that the aforementioned voltage supply times will varydepending on the hydraulic components employed within the stump grinder10. It should also be appreciated that the voltage supply times willalso vary depending on the level of voltage to be supplied.

As a result, the predetermined length of travel controlled by theautomatic depth control circuit 96 is set by a manufacturer of the stumpgrinder 10. It should be appreciated that once set by the manufacturer,each activation of the actuating member 94 will affect the predeterminedlength of travel. Accordingly, the operator of the stump grinder 10 mayopt to “bump” the toggle switch 94A more than once to provide consistentdepth adjustment between lateral passes that are greater than the presetor predetermined adjustment. It should also be appreciated that theautomatic depth control circuit 96 controls may provide for a manualdepth adjustment as well. By way of example, where the operatoractivates and holds the actuating member 94, the vertical movement ofthe cutting assembly 40 will correspond directly to the length of timethe actuating member 94 is held by the operator.

Additionally, it should be appreciated that while the automatic depthcontrol system 86 of the present invention has been described inconnection with having an automatic depth control circuit 96 for depthof the cutting assembly 40, the automatic movement of the presentinvention may be employed in connection with adjusting the axialmovement as well. It should further be appreciated that while theautomatic depth adjustment circuit 96 is employed in connection with thestump grinder 10 having the hydraulic actuating assembly 70, the presentinvention may also be employed in connection with actuating assembliesusing electronic, pneumatic or mechanical actuation.

Referring to FIG. 4, another embodiment, according to the presentinvention, of the automatic depth control system 86 is illustrated. Likenumerals of the automatic depth control system 86 have like referencenumerals increased by one hundred (100). As illustrated in FIG. 4, theautomatic depth control system 186 includes similar structure to theautomatic depth control system 86 shown in FIG. 3. However, theautomatic depth control system 186 illustrated in FIG. 4 includes theautomatic depth control circuit 196 within the controller 190. It shouldbe appreciated that the automatic depth control circuit 196 functions inthe similar manner as that described with respect to the embodimentillustrated in FIG. 3.

As illustrated in FIG. 4, the controller 190 further includes anadjustable automatic depth control dial 198. The adjustable automaticdepth control dial 198 enables the operator to adjust the predeterminedlength of travel regulated by the automatic depth control circuit 196.Accordingly, the operator may adjust the “bump” feature for the toggleswitch 194A between any one of a number of pre-set depths within apredetermined range. It should be appreciated that the predeterminedrange of pre-set depths may extend between less than one half inch tosix inches, with a preferred range between one half inch and three andone half inches. It should be appreciated that the remaining componentsdisclosed with respect to the embodiment illustrated in FIG. 3 areincorporated by reference as though fully set forth with respect to theembodiment illustrated in FIG. 4.

The present invention has been described in an illustrative manner. Itis to be understood that the terminology, which has been used, isintended to be in the nature of words of description rather than oflimitation.

Many modifications and variations of the present invention are possiblein light of the above teachings. Therefore, within the scope of theappended claims, the present invention may be practiced other than asspecifically described.

The invention claimed is:
 1. A method of automatically controlling thedepth of a cutting assembly for a stump grinder, said method comprisingthe steps of: engaging a stump with the cutting assembly; advancing thecutting assembly across the stump; activating a controller toincrementally move the cutting assembly in the vertical direction for apredetermined length of travel; re-engaging the stump with the cuttingassembly; and wherein each incremental adjustment is in response to anoperator input.
 2. A method of automatically controlling the depth of acutting assembly for a stump grinder, said method comprising the stepsof: engaging a stump with the cutting assembly; advancing the cuttingassembly across the stump in a lateral direction; activating acontroller to automatically move the cutting assembly in the verticaldirection for a predetermined length of travel; and re-engaging thestump with the cutting assembly; wherein said step of activating acontroller further includes regulating a duration of a signal sent fromthe controller to a predetermined time that corresponds to apredetermined length of travel of vertical movement of the cuttingassembly.
 3. A method as set forth in claim 1 further including the stepof adjusting an automatic depth control selector to one of a pluralityof pre-set depths to regulate the vertical movement of the cuttingassembly to a predetermined length of travel prior to said step ofactivating.
 4. A method of automatically controlling the depth of acutting assembly for a stump grinder, said method comprising the stepsof: providing an automatic depth controlled cutting assembly for a stumpgrinder comprising: a cutting assembly operatively attached to a stumpgrinder for engaging and grinding a stump; an actuating assembly toactuate movement of said cutting assembly relative to the stump; and anautomatic depth control system cooperating with said actuating assemblyto incrementally and automatically control a depth of said cuttingassembly relative to the stump; engaging a stump with the cuttingassembly; advancing the cutting assembly across the stump in a lateraldirection; activating a controller to incrementally and automaticallymove the cutting assembly in the vertical direction for a predeterminedlength of travel; re-engaging the stump with the cutting assembly; andwhereby grinding of the stump is effectuated by incrementally adjustingthe cutting assembly by the predetermined length of travel, wherein eachincremental adjustment in response to a single operator input.
 5. Amethod of automatically controlling the depth of a cutting assembly fora stump grinder, said method comprising the steps of: providing anautomatic depth controlled cutting assembly for a grinder comprising: acutting assembly operatively attached to a stump grinder for engagingand grinding a stump; an actuating assembly to actuate movement of saidcutting assembly relative to the stump; and an automatic depth controlsystem cooperating with said actuating assembly to automatically controla depth of said cutting assembly relative to the stump; engaging a stumpwith the cutting assembly; advancing the cutting assembly across thestump in a lateral direction; activating a controller to automaticallymove the cutting assembly in the vertical direction for a predeterminedlength of travel; re-engaging the stump with the cutting assembly; andwherein said step of activating a controller further includes regulatinga duration of a signal sent from the controller to a predetermined timethat corresponds to a predetermined length of travel of verticalmovement of the cutting assembly.
 6. A method as set forth in claim 4further including the step of adjusting an automatic depth controlselector to one of a plurality of pre-set depths to regulate thevertical movement of the cutting assembly to a predetermined length oftravel prior to said step of activating.
 7. A method of automaticallycontrolling the depth of a cutting assembly for a stump grinder, saidmethod comprising the steps of: providing a stump grinder comprising: aframe; a cutting assembly operatively supported by said frame; anactuating assembly operatively connected to said frame and said cuttingassembly, said actuating assembly adapted to direct movement of saidcutting assembly relative to a stump; and an automatic depth controlsystem operatively connected to said actuating assembly to automaticallycontrol a depth of said cutting assembly relative to the stump; engaginga stump with the cutting assembly; advancing the cutting assembly acrossthe stump in a lateral direction; activating a controller toautomatically and incrementally move the cutting assembly in thevertical direction for a predetermined length of travel; and repeatedlyalternating between re-engaging the stump with the cutting assembly andrepeatedly re-activating the controller, to incrementally adjust thecutting assembly to a final depth via a plurality of incrementaladjustments to the cutting assembly, each adjustment being initiated byan operator.